Power station runtime calculator
Already looking at a power station? Enter its size and tick what you’d run from it. We’ll show how many hours or days it lasts.
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How runtime is worked out
A power station’s capacity is printed in watt-hours (Wh). Not all of it reaches your devices – some is lost converting battery power into mains power. We assume about 85% is usable.
Runtime in hours = capacity (Wh) × 0.85 ÷ device power (W)
For devices you only use for part of the day, we also show how many days the station lasts at the hours you’ve set.
Typical runtimes on a 1,000 Wh power station
| Device | Typical power | Runs continuously for about |
|---|---|---|
| LED lamp | 8 W | 106 hours |
| Wi-Fi router | 12 W | 70 hours |
| CPAP (no humidifier) | 40 W | 21 hours |
| Laptop | 60 W | 14 hours |
| TV | 80 W | 10 hours |
| Electric heater (low) | 1,000 W | under 1 hour |
These are typical figures. Your own devices may use more or less – check the label or manual.
Making a power station last longer
- Run the biggest users – like the fridge – for a few hours at a time rather than all day. Keep the door closed in between.
- Charge phones and power banks from the station’s USB ports, which avoids the losses of the mains socket.
- Switch off the mains (AC) output when you aren’t using it – the inverter uses power even when idle.
- Top up with a solar panel during the day.
Frequently asked questions
How long will a 1,000 Wh power station run a fridge?
A large fridge-freezer with a poor energy rating uses around 1,100 Wh a day. A 1,000 Wh power station delivers about 850 Wh after conversion losses, so it would run that fridge for roughly 18 hours. A newer, more efficient fridge could run for a day or more – check the annual kWh figure on its energy label.
How long will a power station run a CPAP machine?
A CPAP without a heated humidifier typically uses 30–60 W. At 40 W for 8 hours a night, that’s about 320 Wh a night, so a 1,000 Wh station would last around two to three nights. Using the humidifier uses far more power. Always check your machine’s manual.
How do I work out power station runtime myself?
Multiply the station’s capacity in Wh by about 0.85 to allow for losses, then divide by the device’s power in watts. That gives the number of hours it will run continuously. For example, 500 Wh × 0.85 ÷ 60 W ≈ 7 hours for a laptop.
Why does the runtime say the output is too low?
If the devices you switch on together draw more watts than the station’s continuous output, it will shut off or refuse to power them. Check the output rating (in W) on the station’s specification.
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General guidance only – not a substitute for official or medical advice. See every figure we use and where it comes from.